This invention relates generally to a laminated assembly, and more particularly to a method for making a laminated magnetic core in which the amount of scrap material is minimized.
A laminated magnetic core typically includes three assemblies of laminations connected together. In manufacturing a laminated assembly, the laminations are pressed together within a die. The laminations include precision cut sides/edges which are positioned against chocks of the die. The chocks slightly squeeze, support and position each lamination within the die. Each lamination includes stakes which are pressed into an adjacent lamination so as to connect adjacent laminations together in forming the laminated assembly.
The width of each lamination is slightly larger than the distance between each pair of opposing chocks. A frictional/interference fit is therefore created between the laminations and chocks. The chocks provide the back-pressure support required by the laminations in pushing stakes of one lamination into an adjacent lamination as the laminations are pressed together. When the distance between the sides of the lamination is not properly dimensioned (i.e., more or less than being slightly larger than the distance between an opposing pair of chocks), the lamination cannot be properly seated between the chocks of the die. Under such conditions, the chocks cannot provide the necessary back-pressure to withstand the pressing of its stakes into an adjacent lamination.
The width of a strip of material from which laminations are formed typically has a minimum tolerance of .+-.0.003 inches. Proper chocking, that is, supporting and squeezing of the laminations between the chocks is not possible when the distance between the edges of each lamination varies within this tolerance range.
In order to avoid variation in lamination width, due to variation in strip width, conventional manufacturing techniques provide laminations with precision cut sides using a "cut all around" method. This method requires that the laminations be cut from a strip of material which is wider than the width of the lamination to be formed.
The cut all around method avoids the problem of an impermissible tolerance range by providing a precise distance (width) separating the sides of each lamination. Unfortunately, the excess material produced by the cut all around method (i.e. extra material on each side of the strip which is not used in forming the lamination) ends up as scrap. This scrap adds to the cost of manufacture.
Accordingly, it is desirable to provide an improved method for manufacturing a laminated assembly in which the amount of scrap material is substantially minimized. The method of manufacture should be capable of mass production and easily incorporated into a conventional manufacturing method in producing laminated assemblies.